diff --git a/include/wx/richtext/bitmaps/image_placeholder24x24.xpm b/include/wx/richtext/bitmaps/image_placeholder24x24.xpm
index 9d1cdec489..a281f210ca 100644
--- a/include/wx/richtext/bitmaps/image_placeholder24x24.xpm
+++ b/include/wx/richtext/bitmaps/image_placeholder24x24.xpm
@@ -1,5 +1,5 @@
 /* XPM */
-static char *image_placeholder24x24_xpm[] = {
+static const char *image_placeholder24x24_xpm[] = {
 /* columns rows colors chars-per-pixel */
 "24 24 2 1",
 "  c #7E97A9",